Cogging
Sensoreless is actually not a realy sensoreless
it sense through back emf from phase wires
so it will cause cogging
there is nothing about turbo or low Turn for a cogging problems
the only thing causing cogging is bad sensored wired,
if you try Novak logger, i had expirience if sensored wired incorrectly pluged or disconnected, it will show it's max rpm instead 0 rpm.
So try to replace your sensor wired.
Other than that. Try to use Sensoreless ( without sensored wired ) run test on load.
then compare it with sensored wired pluged.
if sensoreless run test runs better than when you are using sensored wired, it would be your sensored wired mistake.